The most common and most likely answer to this crossword clue is the 7 letter word HORMONE
I've seen this crossword clue in The Times
H
O
R
M
O
N
E
More clues leading to the result HORMONE
- Compound found in hyacinth or moneywort
- Insulin, say, moorhen might produce
- It stimulates hard men with endless cash
- Growth for one in hospital getting no more treatment
- Chemical agent has second name in support needing no introduction
- Doctor’s cutting instrument beginning to extract bodily substance
- Heard working girl lament one cause of sexual arousal
- Possibly a growing factor helping to make author money
- Chemical substance in hospital no more deployed
- We hear call girl complain, pointing to bodily secretion
Buddy explains!

The straight part
We know that "Insulin, say" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case insulin, say = hormone.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does HORMONE mean?
HORMONE noun- Any substance produced by one tissue and conveyed by the bloodstream to another to effect physiological activity.
- A synthetic compound with the same activity.
- Any similar substance in plants.
- To treat with hormones.